Question #ca93b

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Answer 1 · 2017-03-16T08:40:29

Using formula
#2sin^2theta=1-cos2theta#

we get
#sintheta=sqrt(1/2(1-cos(2xxtheta))#

Putting #theta=75#

#sin75=sqrt(1/2(1-cos(2xx75))#

#=sqrt(1/2(1-cos(180-30))#

#=sqrt(1/2(1+cos30)#

#=sqrt(1/2(1+sqrt3/2)#

#=sqrt(1/8(4+2sqrt3)#

#=sqrt(1/(2*2^2)((sqrt3)^2+2*sqrt3*1+1^2)#

#=1/(2sqrt2)sqrt((sqrt3+1)^2)#

#=1/(2sqrt2)(sqrt3+1)#